Backpack power tool

ABSTRACT

A vibration proofing property is provided in a backpack power tool. A backpack power tool has a backpack carrying part  103  which can be carried on user&#39;s back, and a tool body  105  mounted on the backpack carrying part  103 . Elastic members  133, 135  are provided which connect the tool body  105  and a body support region  113  of the backpack carrying part  103 . The elastic members  133, 135  deform by receiving the weight of the tool body  105  and vibration which is caused in the tool body  105  by rotation of the rotator  123 , and thereby reduce transmission of the vibration from the tool body  105  to the backpack carrying part  103.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a backpack power tool which is carried onuser's back and used for a predetermined working operation.

2. Description of the Related Art

As an example of a backpack power tool, Japanese non-examined laid-openPatent Publication No. 2008-2310 discloses a backpack power blower whichis used for cleaning operation of gathering fallen leaves or cut grass.The known backpack power blower mainly includes a backpack carrying partto be carried on user's back, and a tool body having an internalcombustion engine and a blower which is driven by the internalcombustion engine. The tool body is mounted on the backpack carryingpart via a coil spring.

In the above-described known backpack power blower, vibration caused intool body when driving the internal combustion engine is prevent by thecoil spring from being transmitted to the backpack carrying part. In thetool body, however, not only the driving of the internal combustionengine causes vertical vibration, but rotation of the blower causesvibration. The vibration caused by such rotation is not particularlyconsidered in the known art.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to improve a vibrationproofing property in a backpack power tool.

Above-described object can be achieved by the claimed invention.According to the invention, a representative backpack power tool isprovided which includes a backpack carrying part, a tool body, arotator, a driving mechanism, a back contact region, a body supportregion, and an elastic member. The backpack carrying part is carried onuser's back. The tool body is mounted on the backpack carrying part. Therotator is provided as a component of the tool body. The drivingmechanism is provided as a component of the tool body. The drivingmechanism rotationally drives the rotator in a vertical plane. The backcontact region forms part of the backpack carrying part. The backcontact region contacts the back of the user. The body support regionforms part of the backpack carrying part. The body support regionextends transversely from the back contact region. The elastic member isdisposed between the tool body and the body support region. The elasticmember connects the tool body and the body support region. The “backpackpower tool” according to this invention typically represents a backpackpower blower for use in cleaning operation of blowing and gatheringfallen leaves or cut grass, but it may also widely include a backpackbush cutter for cutting grass or mowing lawn, and a backpack power sprayfor spraying agricultural chemicals or herbicide.

According to the invention, the elastic member deforms by receiving theweight of the tool body and vibration which is caused in the tool bodyby rotation of the rotator. Thus, the elastic member reducestransmission of the vibration from the tool body to the backpackcarrying part. The “rotator” according to the invention typicallyrepresents a blower, and it is preferably arranged to rotate in avertical plane. Further, the “driving mechanism” typically represents aninternal combustion engine, but it also suitably includes an electricmotor.

According to this invention, not only as for vibration caused by drivingof the driving mechanism, but as for vibration caused in the directionof rotation (the circumferential direction) by rotation of the rotator,transmission of the vibration from the tool body to the backpackcarrying part can be reduced.

According to a further aspect of this invention, the elastic member maycomprise a coil spring and the coil spring deforms according to springconstants of the coil spring in a compressing direction and a shearingdirection (direction of oblique displacement) and thereby reducestransmission of vibration of the tool body from the tool body to thebackpack carrying part. If the elastic member is formed, for example, ofrubber and arranged to receive vibration by utilizing its deformation inthe shearing direction, its vibration absorbing effect can be enhanced,but its durability may be decreased. According to this invention, byusing the coil spring, the vibration absorbing effect can be enhanced byutilizing its deformation which is caused according to the springconstant in the shearing direction, while the durability can bemaintained.

According to a further aspect of this invention, the coil spring isarranged such that its central axis extends obliquely toward an axis ofrotation of the rotator with respect to the vertical direction when theuser carries the backpack carrying part on the back. According to thisaspect, by such oblique arrangement, the coil spring can rationallyreceive vibration caused in the direction of rotation by rotation of therotator while receiving the weight of the tool body, by deforming in thecompressing direction and the shearing direction.

According to a further aspect of this invention, in the construction inwhich the central axis of the coil spring extends obliquely toward theaxis of rotation of the rotator, at least two coil springs may bearranged on right and left sides of a vertical line passing through(crossing) the axis of rotation of the rotator. According to thisinvention, the coil spring can be arranged to efficiently proofvibration in consideration of the balance of vibration.

According to a further aspect of this invention, the rotator may bearranged on a near side with respect to the back contact region of thebackpack carrying part which contacts the user's back, and the drivingmechanism maybe arranged on a far side. Further, a rotator housing partmay be provided as a component of the tool body and has acircumferential surface for housing the rotator. The elastic member maybe disposed between the circumferential surface of the rotator housingpart and the body support region of the backpack carrying part.According to this aspect, the elastic member can be arranged closer tothe back contact region, so that vibration transmitted to the backpackcarrying part can be effectively avoided from being amplified in thebody support region and transmitted to the back of the user.

According to a further aspect of this invention, the elastic member maybe arranged with reference to the position of a center of gravity of thetool body. The manner in which the elastic member is “arranged withreference to the position of a center of gravity” in this inventionrepresents the manner in which the elastic member is arranged in avertical plane containing the center of gravity. According to thisaspect, the vibration proofing function can be performed in a balancedstate in the fore-and-aft direction and the lateral direction with thebackpack power tool carried on the back of the user.

According to a further aspect of this invention, the rotator comprisesan impeller of the blower, and the driving mechanism comprises aninternal combustion engine. According to this aspect, in the backpackpower blower for use in cleaning operation of gathering fallen leaves orcut grass, not only as for vibration caused by driving of the internalcombustion engine, but for vibration caused in the direction of rotationby rotation of the impeller of the blower, transmission of the vibrationfrom the tool body to the backpack carrying part can be reduced.

According to the invention, a vibration proofing property is improved ina backpack power tool.

Other objects, features and advantages of the present invention will bereadily understood after reading the following detailed descriptiontogether with the accompanying drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an entire backpack power toolaccording to an embodiment of the invention.

FIG. 2 is a side view of the backpack power tool.

FIG. 3 is a vertical section of the backpack power tool when viewed fromthe rear.

FIG. 4 is a perspective view showing the backpack power tool in use.

DETAILED DESCRIPTION OF THE INVENTION

Each of the additional features and method steps disclosed above andbelow may be utilized separately or in conjunction with other featuresand method steps to provide and manufacture improved backpack power tooland method for using such backpack power tool and devices utilizedtherein. Representative examples of the present invention, whichexamples utilized many of these additional features and method steps inconjunction, will now be described in detail with reference to thedrawings. This detailed description is merely intended to teach a personskilled in the art further details for practicing preferred aspects ofthe present teachings and is not intended to limit the scope of theinvention. Only the claims define the scope of the claimed invention.Therefore, combinations of features and steps disclosed within thefollowing detailed description may not be necessary to practice theinvention in the broadest sense, and are instead taught merely toparticularly describe some representative examples of the invention,which detailed description will now be given with reference to theaccompanying drawings.

A representative embodiment of the invention is now described withreference to FIGS. 1 to 4. In this embodiment, a backpack power bloweris described as a representative embodiment of a backpack power toolaccording to the invention. As shown in FIGS. 1 and 2, a backpack powerblower 101 mainly includes a backpack carrier 103 which can be carriedby a user on the back, and a power blower 105 which is mounted on thebackpack carrier 103. The backpack carrier 103 and the power blower 105are features that correspond to the “backpack carrying part” and the“tool body”, respectively, according to the invention.

The backpack carrier 103 is generally L-shaped in side view and includesa back pad part (back contact part) 111 which extends vertically andcontacts the back of the user when carried by the user on the back, anda base 113 which extends horizontally from the lower end of the backcontact part 111 and on which the power blower 105 is mounted. Each ofthe back contact part 111 and the base 113 has a frame structure formedby bending a pipe into a generally square shape. The back contact part111 and the base 113 are features that correspond to the “back contactregion” and the “body support region”, respectively, according to theinvention. As shown in FIG. 5, the backpack carrier 103 further includesa backpack carrying band 115 and is carried on the back of the user viathe backpack carrying band 115. The backpack carrying band 115 isdesigned to be detachable from the back contact part 111. In thefollowing description, for the sake of convenience of explanation, theside of the back contact part 111 (the left side as viewed in FIG. 2) istaken as the front and the extending side (the right side as viewed inFIG. 2) of the base 113 extending from the end of the back contact part111 as the rear.

The power blower 105 mainly includes a blower 121 and an internalcombustion engine 131 that rotationally drives the blower 121. Theinternal combustion engine 131 is a feature that corresponds to the“driving mechanism” according to this invention. As shown in FIG. 3, theblower 121 includes an impeller (hereinafter referred to as a blowerfan) 123 and a housing 125 that houses the blower fan 123. The blowerfan 123 and the housing 125 are features that correspond to the“rotator” and the “rotator housing part”, respectively, in thisinvention.

An air blowoff pipe 128 is connected to an air outlet port 125 a formedin the housing 125, via an elbow pipe 126 and a bellows-like flexiblepipe 127. As shown in FIGS. 1 and 2, an operating member in the form ofa handgrip 129 for operating the blowoff pipe 128 is provided on theblowoff pipe 128. By holding the handgrip 129 and operating a controlmember of the internal combustion engine 131 and the blowoff pipe 128,the user can perform an operation of blowing and gathering fallen leavesor cut grass by air which is blown out through an outlet port 128 a ofthe blowoff pipe 128.

As shown in FIGS. 1 and 2, the blower 121 and the internal combustionengine 131 are arranged one behind the other, or with the internalcombustion engine 131 behind the blower 121. At least outer shellcomponents (housings) of the blower 121 and the internal combustionengine 131 are formed in one piece.

A vibration proofing structure of the power blower 105 which is mountedon the backpack carrier 103 is now described. The vibration proofingstructure according to this embodiment mainly includes a plurality of(two) coil springs 133, 135 disposed between the base 113 of thebackpack carrier 103 and the power blower 105. The coil springs 133, 135are features that correspond to the “elastic member” in this invention.The coil springs 133, 135 deform by receiving the weight of the powerblower 105 and vibration caused in the power blower 105 and can therebyreduce or prevent transmission of the vibration from the power blower105 to the backpack carrier 103.

In this embodiment, the two coil springs 133, 135 deform according tothe spring constants in the compressing direction and in the shearingdirection of the coil springs and thereby reduce or prevent transmissionof vibration which is caused when the power blower 105 is driven, to thebackpack carrier 103. Specifically, as shown in FIG. 3, the two coilsprings 133, 135 are arranged in symmetry with respect to a verticalline P extending vertically through (across) a rotary shaft 123 a of theblower fan 123 and arranged such that the central axes of the coilsprings 133, 135 extend obliquely toward the axis of rotation (therotary shaft 123 a) of the blower fan 123 (such that the central axesform an inverted V-shape when viewed from the front or the rear). Bysuch arrangement, the right and left coil springs 133, 135 receivevertical vibration caused by driving of the internal combustion engine131 and vibration caused in the direction of rotation (thecircumferential direction) by rotation of the blower fan 123 of theblower 121 while supporting the weight of the power blower 105 andthereby deform in the compressing direction and in the shearingdirection (the direction of oblique displacement). By such deformation,transmission of the vibration from the power blower 105 to the backpackcarrier 103 can be reduced or prevented.

The right and left coil springs 133, 135 are disposed between the uppersurface of the base 113 of the backpack carrier 103 and the lowersurface of the circumferential surface region of the housing 125 whichhouses the blower fan 123. The coil springs 133, 135 are fastened at oneaxial end to the upper surface of the base 113 via spring receivingbracket 133 a, 135 a and at the other end to the lower surface of thehousing 125 via spring receiving bracket 133 b, 135 b.

Further, one coil spring (not shown) is disposed generally in the middlein the lateral direction (on a vertical line passing through (crossing)the axis of rotation of the blower fan 123) between a rear surface of anupper end portion of the back contact part 111 of the backpack carrier103 and a front surface of an upper end portion of the housing 125 ofthe blower 121 and arranged such that the central axis of the coilspring extends generally horizontally in the fore-and-all direction.Specifically, the power blower 105 is supported at two points on thebase 113 and one point on the back contact part 111 by the coil springs133, 135, and it is held contactless at any other points with respect tothe backpack carrier 103.

In this embodiment, the power blower 105 is mounted on the backpackcarrier 103 via the coil springs 133, 135, and the coil springs 133, 135deform by receiving the weight of the power blower 105 and vibrationcaused in the direction of rotation by rotation of the blower fan 123and can thereby prevent transmission of the vibration from the powerblower 105 to the backpack carrier 103. Further, in this embodiment, thecoil springs 133, 135 are arranged such that the central axes of thecoil springs 133, 135 extend obliquely toward the axis of rotation ofthe blower fan 123. With this arrangement, the coil springs 133, 135 candeform in the compressing direction and in the shearing direction andthereby absorb vertical vibration caused by driving of the internalcombustion engine 131 and vibration caused in the direction of rotationby rotation of the blower fan 123, so that transmission of the vibrationfrom the power blower 105 to the backpack carrier 103 can be reduced.

Further, in this embodiment, it is constructed such that vibration isabsorbed by deformation of the coil springs 133, 135 in the compressingdirection and in the shearing direction. If the vibration-proofingmember is formed, for example, of rubber and arranged to receivevibration by utilizing its deformation in the shearing direction, itsvibration absorbing effect can be enhanced, but its durability may bedecreased. According to this invention, by using the coil springs 133,135, the vibration absorbing effect can be enhanced by utilizingdeformation which is caused according to the spring constant in theshearing direction, while the durability can be maintained.

In this embodiment, the two coil springs 133, 135 are arranged insymmetry with respect to the vertical line P extending through the axisof rotation of the blower fan 123. Therefore, the weight of the powerblower 105 and vibration caused by driving the power blower 105 can bereceived in a balanced manner in the lateral direction. Such asymmetrical arrangement is effective, for example, if the center ofgravity of the power blower 105 lies on the vertical line P. Actually,however, the center of gravity of the power blower 105 may be displacedto the right or the left off the vertical line P. Therefore, in such acase, preferably, the two coil springs 133, 135 are arranged in aposition to achieve right and left weight balance with respect to thevertical line P, so that efficient vibration proofing can be realized.

Further, vibration is not always caused in the same manner on the rightand left sides of the vertical line P. For example, the manner ofvibration on the side having the air outlet port 125 a differs from thaton the other side not having the air outlet port 125 a. Further, thedirection of vibration acting on the left coil spring 133 differs fromthat on the right coil spring 135 according to the direction of rotationof the blower fan 123 (In FIG. 3, because the blower fan 123 rotatesclockwise, vibration acts upward on the left coil spring 133 anddownward on the right coil spring 135). Therefore, preferably, the rightand left coil springs 133, 135 are adjusted in position and angle anddisposed such that efficient vibration proofing can be achieved byreceiving vibration evenly on the right and left sides.

Further, in this embodiment, the blower 121 and the internal combustionengine 131 are arranged one behind the other, or with the internalcombustion engine 131 behind the blower 121, and the circumferentialsurface of the housing 125 of the blower 121 is supported by the coilsprings 133, 135. With this construction, the distance from the backcontact part 111 of the backpack carrier 103 to the coil springs 133,135 can be made shorter, for example, compared with a construction inwhich the coil springs 133, 135 support the internal combustion engine131. Therefore, vibration transmitted to the base 113 of the backpackcarrier 103 can be avoided from being amplified at the base 113 andtransmitted to the back of the user, and heat generated in the internalcombustion engine 131 can also be avoided from adversely affecting theuser.

The invention is not limited to the above-described embodiment, but canbe appropriately modified or changed. For example, in this embodiment,the circumferential surface of the housing 125 of the blower 121 issupported by the coil springs 133, 135, but it may be modified such thatthe coil springs 133, 135 are arranged in symmetry with respect to avertical line passing through the center of gravity of the power blower105. In this case, the weight of the power blower 105 and vibrationcaused by driving the power blower 105 can be received not only in thelateral direction but in the fore-and-aft direction in a balancedmanner.

Further, in this embodiment, the base 113 is formed to extend rearwardfrom the lower edge of the back contact part 111, and the power blower105 is mounted on the upper surface of the base 113. It may however bemodified, for example, such that a support part is formed to extendrearward from the upper edge of the back contact part 111 and the powerblower 105 is hung and supported via the coil springs 133, 135 withrespect to the support part. In this case, preferably, the coil springs133, 135 are arranged in symmetry with respect to the vertical line Ppassing through the axis of rotation of the blower fan 123 such that thecentral axes of the coil springs extend obliquely toward each other toform a V-shape when viewed from the front or the rear. Further, themeans for driving the blower 121 may be an electric motor in place ofthe internal combustion engine 131.

Further, in this embodiment, the backpack power blower is described as arepresentative example of the backpack power tool according to theinvention. However, the invention can be applied not only to thebackpack power blower, but to a backpack bush cutter for cutting grassor mowing lawn, or a backpack power sprayer for spraying agriculturalchemicals or herbicide.

DESCRIPTION OF NUMERALS

-   101 backpack power blower-   103 backpack carrier (backpack carrying part)-   105 power blower (tool body)-   111 back contact part (back contact region)-   113 base (body support region)-   115 backpack carrying band-   121 blower-   123 blower fan (rotator)-   123 a rotary shaft-   125 housing-   125 a outlet port-   126 elbow pipe-   127 flexible pipe-   128 blowoff pipe-   128 a outlet port-   129 handgrip-   131 internal combustion engine (driving mechanism)-   133 coil spring (elastic member)-   135 coil spring (elastic member)-   133 a, 133 b spring receiving bracket-   135 a, 135 b spring receiving bracket

1. A backpack power tool comprising: a backpack carrying part carried on user's back, a tool body mounted on the backpack carrying part, a rotator provided as a component of the tool body, a driving mechanism provided as a component of the tool body to rotationally drive the rotator in a vertical plane, a back contact region which forms part of the backpack carrying part and contacts the back of the user, a body support region which forms part of the backpack carrying part and extends transversely from the back contact region, and an elastic member which is disposed between the tool body and the body support region and connects the tool body and the body support region, wherein the elastic member deforms by receiving the weight of the tool body and vibration which is caused in the tool body by rotation of the rotator, and thereby reduces transmission of the vibration from the tool body to the backpack carrying part.
 2. The backpack power tool according to claim 1, wherein the elastic member comprises a coil spring, and the coil spring deforms according to spring constants of the coil spring in a compressing direction and a shearing direction and thereby reduces transmission of vibration of the tool body from the tool body to the backpack carrying part.
 3. The backpack power tool according to claim 2, wherein t the coil spring is arranged such that its central axis extends obliquely toward an axis of rotation of the rotator with respect to a vertical direction when the user carries the backpack carrying part on the back.
 4. The backpack power tool according to claim 3, wherein two coil springs are respectively arranged on right and left sides of a vertical line passing through the axis of rotation of the rotator.
 5. The backpack power tool according to claim 1, wherein the rotator is arranged on a near side with respect to the back contact region of the backpack carrying part which contacts the user's back, and the driving mechanism is arranged on a far side, wherein the backpack power tool further includes a rotator housing part provided as a component of the tool body and having a circumferential surface for housing the rotator, and wherein the elastic member is disposed between the circumferential surface of the rotator housing part and the body support region.
 6. The backpack power tool according to claim 1, wherein the elastic member is arranged with reference to the position of a center of gravity of the tool body.
 7. The backpack power tool according to claim 1, wherein the rotator comprises an impeller of the blower, and the driving mechanism comprises an internal combustion engine. 